Systems and methods for determining, broadcasting and using reference atmospheric data in a network of transmitters

Abstract

Determining, broadcasting and using reference pressure data in a network of transmitters. Particular embodiments described herein include machines that select atmospheric data from weather stations within a transmitter network, use the selected atmospheric data to determine a reference atmospheric value, and transmit the reference atmospheric value from a transmitter to a mobile device for use in estimating an altitude of the mobile device. The atmospheric data may include any of reference pressures form the weather stations, measured temperatures from the weather stations, or reference temperatures from the weather stations. The reference atmospheric value may include a reference pressure value of a reference altitude, or a reference temperature value.

The invention claimed is: 
     
       1. A method for determining, broadcasting and using reference atmospheric data in a transmitter network, wherein the method comprises:
 selecting reference data from one or more weather stations, 
 wherein the reference data includes one or more of a reference pressure the one or more weather stations, or a measured temperature from each of the one or more weather stations; 
 using the selected reference data to determine a reference value, 
 wherein the reference value includes one or more of a reference pressure value of a reference altitude, or a reference temperature value; and 
 transmitting the reference value from a transmitter of the transmitter network to a mobile device; 
 wherein the selecting reference data from one or more weather stations within the transmitter network to be used in determining one or more reference values comprises: 
 determining a cellular element associated with the transmitter, 
 wherein the cellular element is a location of the transmitter, a coverage area of the transmitter, a cell sector of the transmitter, or a beam of the transmitter; and 
 selecting reference data that meet a proximity condition relative to the cellular element. 
 
     
     
       2. The method of  claim 1 , wherein the method further comprises:
 after transmitting the reference value, determining if a broadcast is scheduled at a first time; and 
 if a broadcast is scheduled at the first time:
 selecting new reference data from one or more weather stations within the transmitter network; 
 using the new reference data to determine a new reference value; and 
 transmitting the new reference value from the transmitter to the mobile device or another mobile device. 
 
 
     
     
       3. The method of  claim 1 , wherein the method further comprises:
 after transmitting the reference value, determining if a broadcast is scheduled at a first time; 
 if a broadcast is scheduled at the first time, determining if the reference value is valid; 
 if the reference value is valid, transmitting the reference value from the transmitter to the mobile device or another mobile device; and 
 if the reference value is not valid:
 generating a new reference pressure value; and 
 transmitting the new reference pressure value from the transmitter to the mobile device or the other mobile device. 
 
 
     
     
       4. The method of  claim 1 , wherein the method further comprises:
 after transmitting the reference value, determining if the reference value is valid; 
 if the reference value is valid, transmitting the reference value from the transmitter to the mobile device or another mobile device; and 
 if the reference value is not valid:
 generating a new reference pressure value; and 
 transmitting the new reference pressure value from the transmitter to the mobile device or the other mobile device. 
 
 
     
     
       5. The method of  claim 1 , wherein the method further comprises:
 after transmitting the reference value, determining if a broadcast is scheduled at a first time; 
 if a broadcast is not scheduled at the first time, determining if the reference value is valid; 
 if the reference value is valid, determining if a broadcast is scheduled at a second time that is after the first time; and 
 if the reference value is not valid:
 generating a new reference value; and 
 determining if a broadcast is scheduled at the second time. 
 
 
     
     
       6. The method of  claim 1 , wherein selecting reference data that meet a proximity condition relative to the cellular element comprises:
 selecting only reference data from each weather station within the cellular element or within a threshold distance from part of the cellular element. 
 
     
     
       7. The method of  claim 1 , wherein selecting reference data that meet a proximity condition relative to the cellular element comprises:
 selecting only reference data from the nearest n weather stations to part of the cellular element. 
 
     
     
       8. The method of  claim 1 , wherein the reference data is selected based on an age or a quality in addition to the proximity condition, and selecting reference data comprises:
 selecting only reference data with an age that is below a threshold age value, selecting only the n most-recently provided reference data, selecting only reference data with a quality that is above a threshold quality value, or selecting only the n highest-quality reference data. 
 
     
     
       9. The method of  claim 1 , wherein if no reference data meet the proximity condition, the method comprises:
 determining a new cellular element; and 
 selecting reference data that meet the proximity condition relative to the new cellular element. 
 
     
     
       10. The method of  claim 3 , wherein the determining if the reference value is valid comprises:
 determining a time at which an atmospheric condition in the transmitter network is expected to change by a threshold amount of the atmospheric condition since the reference value was determined, 
 wherein the atmospheric condition is pressure when the reference value is a reference pressure value, or the atmospheric condition is temperature when the reference value is a reference temperature value; and 
 determining, based on the determined time, an expiration time for the reference value before which the reference value is valid and after which the reference value is invalid, 
 wherein the expiration time is the determined time or a time that precedes the determined time by a threshold amount of time. 
 
     
     
       11. The method of  claim 3 , wherein the reference value is a reference pressure value, and wherein generating a new reference value comprises:
 adjusting the reference pressure value by an amount of pressure change that occurred in the network since the reference pressure value was determined, 
 wherein the new reference pressure value is the result of adjusting the reference pressure value. 
 
     
     
       12. The method of  claim 3  wherein the selected reference data includes selected reference pressures, wherein the reference value is a reference pressure value, and wherein generating a new reference value comprises:
 for each reference pressure of the selected reference pressures that originated from an area in which pressure changed in excess of a threshold amount of pressure since that reference pressure was determined, adjusting that reference pressure by an amount of pressure change that occurred since that reference pressure was determined; and 
 computing the new reference pressure value using the adjusted reference pressures. 
 
     
     
       13. The method of  claim 1 , wherein the selected reference data includes selected reference pressures, wherein the reference value is a reference pressure value of a reference altitude, and wherein the method further comprises:
 receiving, at the mobile device, the reference pressure value that was transmitted by the transmitter; 
 determining if the reference pressure value is valid at a current time; 
 if the reference pressure value is valid:
 determining a first representative reference pressure value using the reference pressure value received from the transmitter, and 
 using the first representative reference pressure value, the reference altitude, and a pressure value measured by a pressure sensor of the mobile device to estimate an altitude of the mobile device; and 
 
 if the reference pressure value is not valid:
 determining a new reference pressure value by adjusting the reference pressure value received from the transmitter based on changes in pressure in the network, 
 determining a second representative reference pressure value using the new reference pressure value, and 
 using the second representative reference pressure value, the reference altitude, and the pressure value to estimate the altitude of the mobile device. 
 
 
     
     
       14. The method of  claim 13 , wherein determining if the reference pressure value is valid comprises:
 (i) (a) receiving, from the transmitter, an expiration time of the reference pressure value, and (b) determining that the reference pressure value is valid if the current time is before the expiration time, and determining that the reference pressure value is invalid if the current time is after the expiration time; or 
 (ii) (a) determining a time at which pressure in the network is expected to change by a threshold amount of pressure since the reference pressure value was determined; (b) determining, based on the determined time, an expiration time for the reference pressure value before which the reference pressure value is valid and after which the reference pressure value is invalid, wherein the expiration time is the determined time or a time that precedes the determined time by a threshold amount of time; and (c) determining that the reference pressure value is valid if the current time is before the expiration time, and determining that the reference pressure value is invalid if the current time is after the expiration time. 
 
     
     
       15. The method of  claim 13 , wherein determining a first representative reference pressure value comprises:
 (i) (a) selecting, from m received reference pressure values, the n most-recently determined reference pressure values, wherein m is greater than n, and wherein the n reference pressure values include the reference pressure value received from the transmitter; and (b) computing the first representative reference pressure value by combining the n selected reference pressures; 
 (ii) (a) selecting, from m received reference pressure values, the n reference pressure values having the longest validity times, wherein m is greater than n, and wherein the n reference pressure values include the reference pressure value received from the transmitter; and (b) computing the first representative reference pressure value by combining the n selected reference pressures; or 
 (iii) (a) selecting, from m received reference pressure values, the n reference pressure values from n respective transmitters that are closet to an estimated location of the mobile device, wherein m is greater than n, and wherein the n reference pressure values include the reference pressure value received from the transmitter; and (b) computing the first representative reference pressure value by combining the n selected reference pressures. 
 
     
     
       16. The method of  claim 13 , wherein determining a new reference pressure value comprises:
 (i) adjusting the reference pressure value by an amount of pressure change that occurred since the reference pressure value was determined, wherein the new reference pressure value is the result of adjusting the reference pressure value; 
 (ii) (a) determining an estimated position of the mobile device; (b) determining an expected amount of change in pressure between the estimated position of the mobile device and a previous estimated position of the mobile device at which the reference pressure value was received; and (c) adjusting the reference pressure value by the expected amount of change in pressure, wherein the new reference pressure value is the result of adjusting the reference pressure value; or 
 (iii) (a) determining an estimated position of the mobile device; (b) determining an expected amount of change in pressure between the estimated position of the mobile device and the transmitter; and (c) adjusting the reference pressure value by the expected amount of change in pressure, wherein the new reference pressure value is the result of adjusting the reference pressure value. 
 
     
     
       17. One or more non-transitory machine-readable media embodying program instructions that, when executed by one or more machines, cause the one or more machines to implement the method of  claim 1 .